مجله مدیریت اراضی
سال دهم شماره 1 (بهار و تابستان 1401)

The present paper investigates soil valuation and explores the intricacies associated with the development of a standard framework for a sound soil valuation system. Drawing upon a review of studies conducted across the world, we identify the techniques commonly used in estimating the economic value of soil that best suits the conditions in Iran. The ‘ecosystem services’ and ‘total economic value’ (TEV) frameworks are being currently employed for economic valuation of environmental resources and that of soil as the main component of the environment. A variety of methods have been developed for estimating the economic profits of ecosystem services and the costs arising from ecosystem degradation. In most cases, base cost estimation involves replacement cost, opportunity cost, damage cost avoid, and replacement cost methods. Study of the implementation of these methods as well as their associated requirements including soil nutrient content and current land use as well as soil conservation and watershed management practices in use reveal that the above methods can be effectively implemented because not only the required infrastructure but also the necessary data are currently available at the state-level. A salient feature of these methods is that they guarantee more tangible and calculable advantages, basic significance for environmental resources, and non-recurrent concerns about environmental commodities; care must, however, be taken in the measurement system employed for the monetary value of resources during environmental assessment since only investment and labor revenues are taken into account while the revenues due to the exploitation of vital resources and services are ignored and never ever included in the absence of a pricing policy, which obviously causes the values of natural resources to remain unaccounted for in economic estimations.

In congruence with the idea of sustainable development, integrated soil fertility and plant nutrition management has received global attention. The challenges facing soil fertility and plant nutrition in Iran include low soil organic carbon and nutrient contents, imbalanced plant nutrition, low nutrient efficiency, ineffective soil fertility system, environmental stresses, non-efficient fertilizer application, and inadequate knowledge transfer to users. Under these conditions, recommending proper fertilizers will be a multi-faceted and complex task. The development of a framework that incorporates all the factors involved into a single management package is the prerequisite to the integrated soil fertility and plant nutrition management as a smart system for applying an optimal assortment of chemical, organic, and biological sources of nutrients well adapted to environmental and local conditions and aimed at optimized exploitation of inherent soil capacities in a cropping system while sparing negative effects on soil ecological services. The desired integrated management system must be capable of duly accounting for all the components including plant variety; chemical, organic, and biological fertilizers; cropping system; climatic and soil conditions; and socio-economic parameters. The present study introduces the following three steps to achieve an integrated management system: 1) participation of all the stakeholders in the design, prioritization, implementation, and monitoring processes; 2) integrated use of chemical, organic, and bio-fertilizers in terms of amounts, timing, and method of application well adapted to the nutritional requirements of the plant varieties grown in the established cropping system with due consideration of environmental stresses; and 3) dissemination of localized knowledge and know-how of the integrated management system with the help of local extensionists and volunteer farmers from a pilot farm for replication and achievement of the expected outcomes in other farming sites.

With the new concepts and goals defined under global ecosystem sustainability and the potential contributions of soil ecosystems to the sustainability of nature and natural resources, efforts have been made to redefine the role of the science of evaluation in achieving the goals thereby defined. Introducing the components of a sustainable ecosystem, the present study strives to explore the functions of soil ecosystem and to define the role of land assessment in developing a road map toward environmental sustainability. Although the science of evaluation serves as the foundation for decision and policy making processes, it has not yet been properly and systematically exploited to achieve optimally integrated resource management. Environmental assessment, no matter how it is employed, is still the missing link in decision and policy making processes as part of sustainable resource management. It, indeed, requires due consideration in all such processes as it plays a pivotal role in bridging all environmental, economic, and engineering disciplines. Land evaluation is a disciple that characterizes soil composition in terms of its quality, degradation, flexibility, safety, health, productivity, behavior, and efficiency and, in conjunction with an evaluation of soil ecosystem functions, defines the roles each of the soil characteristics plays in integrated land management.

Many factors are involved in the production of healthy crop products and their monitoring requires a process-based and systemic approach at all stages from site selection to consumption. The present paper draws upon national and international experiences reflected in reviews in order to identify the most important factors affecting crop quality; the results will be expectedly exploited toward designing future studies and developing measures to improve crop qulity. Soil is the medium in which agricultural production takes place. Although geological formations with high concentrations of pollutants (especially heavy metals) might pollute soil resources, human activities inlcuding polluting industrial activities, improper application of agricultural inputs such as pesticides, chemical and organic fertilizers (especially phosphate fertilizers and non-standard sewage sludge), undertreated effluents, and atmospheric deposits (especially in urban and peri-urban areas) are some of the factors that expose soil and agricultural production more severely to the adverse of effects of such pollutants. Water pollution cannot be divorced from that of soil as they are closely related. While certain reports attribute soil pollution in parts of Iran solely to heavy metals with geohydrological origins, long-time crop irrigation using wastewater with high pollutant loads should not be ignored as a serious source of soil pollution. It should be noted that management plays a pivotal role in growing healthy products via using healthy inputs while maintaining biodiversity but that this cannot be achieved in the absence of such healthy basic resources as: a) soil, b) water, and c) air. In other words, unhealthy crops with pollutant loads result from both production processes and the environmental factors affecting them. A review of some domestic studies revealed that extensive background experience is required in the various sampling, measurement, and reporting skills, given the high sensitivity of these processes, to arrive at sound interpretations of the results of nitrate and heavy metals concentrations reported in some domestic journals. These studies have reported high concentrations of nitrate in spinach, lettuce, and celery but lower concentrations in such fruits as tomatoes, watermelon, and cantaloupe. Crops such as cucumbers, celery, and potatoes reportedly accounted for the highest nitrate concentration exceeding the allowable nitrate limits but minimum levels in tomatoes, watermelons, and cantaloupes. This is while heavy metal contaminations in plants have not been extensively reported on. Production of crops with allowable limits of pollutants presupposes due consideration of the factors outlined above. The approach proposed in this article requires soil fertility management, proper selection of crop species and cultivars, prohibited farming in contaminated lands, and avoidance of soil exposure to atmospheric deposition and polluted waters. These goals, in turn, may be achieved through accurate monitoring of agricultural product quality and identification of high-risk farming regions.

Legumes, as the main components of human diet, have of long been planted in rotation with other crops. An important characteristic of legumes is their capacity to establish a symbiotic relationship with rhizobium bacteria to fix nitrogen. Proper management of this relationship in soil is a major step toward sustainable agriculture and environmental protection. The discovery and isolation of rhizobium dates back to 130 years ago and it was only a few years later that the first rhizobium containing biofertilizer was made available to the market. In Iran, the biofertilizer was first imported in the 60s for application to soya farms. The abundance of research over the past few decades indicates enhanced performance of legumes as a result inoculating them with rhizobia. The need for rhizobium inoculation may be explained by the lack of especially symbiotic rhizobium bacteria in soils, their low soil populations, and their death or degraded efficiency through time due to environmental stresses. Rhizobium-enriched biofertilizers come in the different forms of liquid, powder, and granules contained in mineral or organic carriers used for seed inoculation. The vast area under legume cultivation, availability of the infrastructure required for biofertilizer production, availability of professionals and technical know-how, public acceptance of organic agricultural crops, and the support mechanisms and incentives provisioned in national macro-policy documents may be claimed as potential motivations for the production and consumption of rhizobium biofertilizers in Iran. However, abundance and rapid productivity of chemical fertilizers, current challenges facing the commercialization of such products, and low consumer awareness and confidence may be claimed as the limitations of such biofertilizers. The following procedures may be recommended for the consumption of rhizobium-containing biofertilizers: conducting surveys of soils from different regions to determine the presence of rhizobia that might be symbiotic with legume crops, investigating the inoculation of target legume seeds with efficient and symbiotic rhizobia, investigating the possibility of cultivating legumes in favorable regions with no history of legume cropping, conducting basic research on indigenous soil bacteria and their competition with rhizobium strains introduced into soils, carrying out molecular research to enhance the symbiotic capacity of legumes, and education and extension activities through both mass and social media to raise public awareness of the advantages of rhizobium biofertilizers.

Iran, is located in the arid and semi-arid regions of the world, so due to geological and topographic conditions, has various and extensive limitations in soil resources and lands. These restrictions, along with unprincipled and intensive exploitation over the past few decades, have posed many challenges to these resources and thus endangered food security and public health. In this article, while briefly stating the importance and functions of soil, the current situation, and the most important challenges and limitations of soil resources in the country are explained. According to available information and data, soil water and wind erosion is the most important cause of soil degradation in Iran, which has many economic, social and environmental consequences. The lowest soil erosion estimated in the country is much higher than its tolerable (average amount of soil formation). The most important cause of soil degradation in agricultural lands, especially irrigated farms, is soil salinity. At least 50% of the country's irrigated lands are facing an increasing problem of salinity. Land use change can be considered as the most important and urgent challenge of the soil resources, especially fertile lands, which also has negative economic, social, cultural and security consequences. Lack of organic carbon and loss of soil fertility, especially agricultural lands, are important limitations of soil quality that severely threaten food security and health. The degradation of soil resources has not only affected its productive function, but has also drastically reduced the capacity of lands and territories to cope with climate change, drought and floods. Occurrence of floods with a frequency greater than the return period of rainfall events, as well as hydrological and agricultural droughts, more severe than climatic droughts, are signs of this degradation.